stdin

stdin.txt

void *av_x_if_null(const void *x, const void *y)
{
	return (void *) (x ? x : y);
}

#define WARN_IF_TYPES_DIFFER(x,y) ((void) sizeof(x == y))

#define av_x_if_null_warn(x,y) \
	( \
		WARN_IF_TYPES_DIFFER(x, y), \
		av_x_if_null(x, y) \
	)

int main(void)
{
	int *a = 0;
	char *b = 0;
	int *i = av_x_if_null_warn(a, a); // fine
	short *c = av_x_if_null_warn(i, b);
	return c ? 1 : 0;
}